Aero-propeller efficiency-indicator



T. P. HORNE; AERO PROPELLER EFFICIENCY INDICATOR.

APPLICATION FILED SEPT-1,1920.

Patented Sept. 6, 1921.

2 SHEETSSHEET I.

Theodora P.Hnrne gwuwntoz Gm we T. P. HORNE.

AERO PROPELLER EFFICI ENCY INDICATOR. APPLICATION FILED SEPT-H1920.

PatentedSept. 6, 1921.

2 SHEETSSHEET 2- M Theodore BHCII'IIE l E 8 4/ 53' /8 I v C lflozmnfsuch an apparatus,

UNITED STATES THEODORE P. HORNE, OF NEWPORT NEWS, VIRGINIA.

AERD-IRQIPELLER EFFICIENCY-INDICATOR.

Specification of Letters Patent.

Application filed September 1, .1920. Serial No. 407,494.

Toallwhamz' tmayconcem: I

Be it known that I, THEODORE PHILIP HORNE. a citizen of the UnitedStates, residing at New ort News, in the county of Warwick and tate ofVirginia, have invented certain new and useful Im rovements inAero-Propeller Efiiciency-fndicators, of which the following is aspecification.

The present invention relates to an apparatus for use on airplanes orother airships, for testing the efiiciency' of the propeller andobtaining calculations as to the efficiency and slip-o the propeller, inorder that the most efiicient propeller can be constructed or selected.

Another object is the provision of such an apparatus'which willgreatlyaid in the development of the airplane, by testing and indicatingthe efliciency of the propeller used, and guiding the engineer ordesigner in the proper construction of the propeller to be used for theparticular type of airlane.

A further object is the provision of such an apparatus including meansoperated with the airplane propeller and its engine, means operated bythe relative motion and speed of the air and airship, and a differentialindicator-controlled by both of said means whereby to indicate theefficiency and slip of the propeller. v

A still further object is the employment of electrical generators, oneoperated with the airplane propeller and its engine, and the otherdriven by a free propeller operated by the relative motion and speedofthe air and airplane, with an electrical differential galvanometercontrolled by both generators for indicating the efliciency due to thedifferences in elec-' trical energy generated.

With the foregoing and other objects in view, which will be apparent asthe description proceeds, the invention resides in the construction andarrangement of parts hereinafter described and claimed, it beingunderstood that changes can be made within the scope of what is claimedwithout departing from the spirit of the invention.

The invention is illustrated in the accompanying drawings, whereinFigurel is a perspective view of an airplane, showing the two electricalgenerators installed thereon.

the airplane,

-Fig. 2 is a diagrammatical view of the two electrical circuits.

Fig. 3 is a frontview of the differential galvanometer or indicatorproper, portions being broken away. F Fig 4 is a section on the line 4-4of Fi 5 is an elevation of the free electrica generator.

In carrying out the invention, two devices are employed, one of which'isoperated with the airplane propeller and the engine, and the other beingfree and operated by the relat1 ve motion and speed of the airplane andarr. In the apparatus as shown, these devices constitute electricalgenerators, and one generator 10 is suitably mounted inor on theairplane and is operatively connected, as at 11, with a shaft 12 of theengine which drives the propeller 13, whereby said generator 10 isoperated with the propeller and engine at a speed proportional to thepropeller speed. The second electrical generator 14; is also suitablymounted in or on referably on one wing thereof, as seen in ig. 1, andits body or casing is of stream line form,iso as to offer leastresistance to the air, and a free propeller 15 is secured on thearmature shaft 16 of the generator 14, whereby to be operated by therelative motion of the air and airplane, and

at a speed proportional to the relative speed of the air-and airplane.Thus, one generator is operated at a speed dependent on the speed of thepropeller 13, while the other generator is free of the engine and isoperated at a speed proportional to the relative speed of the air andairplane. Such generators can be of any suitable voltage and amperage.

A differential indicator is employed for indicating the differencebetween the operation of the two devices or generators operated with thepropellers 13 and 15, and with the electrical generators, a differentialgalvanometer is used, and this galvanometer -or indicating .device 17has the'balanced armature coils 18 disposed in the electrical PatentedSept. 6, 1921.

circuits 19 of the two generators lOand 14,

as seen in Fig. 2, and said coils 18 and generators. are connected inseries with variable resistance 20, for calibrating the electricalcurrent of the two circuits to obtain a proper balance for neutralconditions.

The detail construction of the differential galvanometer is shown inFigs. 3 and 4, said galvanometer including a suitablecase 21 having anoutstanding annular flange 22 at its front edge, for attaching thegalvanometer to an instrument board or other support, and a dial plateor disk 23 is fitted within the mouth of the case 21, being providedwith a forwardly-extending marginal flange 24 fitting the rim of thecase 21 and holding a glass or othertransparent panel 25. The plate 23carries an arcuate scale 26 containing graduations 27 reading from onehundred per centefliciency down to zero in opposite directions from aninter mediate or neutral point, for indicating positive and minusefficiency at the opposite sides of such neutral point, and said scalehas a complementary series of graduations 28 indicating the loss ofefiiciency or slip running from zero at the neutral point to one hundredper cent. in the opposite directions for indicating positive and minusslip, .as seen in Fig. 3. A pointer or index 29 is movable along thegraduations .for simultaneously indicating either positive or minusefiiciency and corresponding slip.

The pointer or index 29 is connected to the armature 30 of thegalvanometer on which the coils 18 are wound, whereby said coils whenequally energized, will result in an electrical balance of thegalvanometer, with the pointer 29 at neutral position, as seen in Fig.3. The pointer 29 is offset, to pass through a slot 30' free end of thepointer between said plate 23 and panel 25, and the opposite end of'thepointer connected to the armature 30 behind said plate 25. The armature30 is rotatably mounted between the pole pieces 31 of a permanenthorseshoe magnet 32 mounted within the case 21 in rear of the plate 23,and a base 33 is secured to the lower ends of the magnet 32 and has.posts 34 supporting bearings 35 for the ends of the armature shaft 36,whereby to support the armature from free turning movement with minimumfriction.

Collector rings 37 are mounted on the armature shaft 36 towhichterminals of the coils 18 are connected, and brushes 38 carried bythebase 33 bear against said rings and are connected by wires 39 tobinding posts 40 on the back of the case 21, for the connection of theother wires or conductors of the electrical circuits 19. The pointer 29has a balancing weight 41 (or a spring can be used), whereby in theabsence of electrical current flowing through the coils or windings 18,or the flow of equal current through said coils, the pointer 29 willremain at, the neutral osition, thereby mechanically and electricallybalancing the armature.

In using the apparatus,

with the airplane in flight, the generator 10 being driven at a in theplate 23, with the b of the airplane propelling speed proportional tothe speed of the ropeller 13, and the generator 14 being driven at aspeed proportional to the relative speed of the air and airplane, due tothe movement of the propeller 15, will energize the two coils 18 of thegalvanometer accordingl and if each propeller 13 is fully eflicent, theelectrical current generated by the generator 10 will balance thecurrent generated by the generator 14, so that the pointer 29. willindicate one hundred per cent. efiiciency and zero slip. Theenergization of the coils 18 will thus neutralize one another, showingthe greatest efliciency for the particular engine speed at which thepropeller 13 is running. Should the propeller 13 and nerator 10 op'eraterelatively faster than the generator 14 and propeller 13, the electricalcurrent generated by the generator 10 will energize the correspondingcoil 18 greater than the other, thereby'swinging the pointer 29 toindicate positive efiiciency (toward the right in Fig. 3) and the fasterthe generator 10 and propeller 13 rotate with respect to the generator14, the less will become the positive eflicienc and the greater willbecome positive slip, as the pointer 29 moves toward the right in Fig.3. Should the propeller 13 and nerator 10 move relatively slower than te generator 14 and propeller 15, the pointer 29 will move to the minusgraduations, due to the fact that the electrical energy from thegenerator 14 will e stronger than that from the generator 10, wherebythe unequal energization of the 100 coils 18 will move the pointer 29toward the left, as seen in Fig. 3. In this way, the galvanometerindicates, due to differences in electrical energy from the two sources,the positive or minus efliciency of the propeller 105 for variousspeeds, and the corresponding slip. The proper form or type of.propeller can thus be selected or designed to most efliciently serve theurpose, and to provide for economyin fue by eliminating 11 the loss inpropeller efficiency due to resistance, friction, or the like. Theapparatus is thus valuable to the airplane designer or engineer intesting propellers and selecting or designing the most efficientpropeller 115 for the particular type of airplane.

Having thus describedthe invention, what is claimed as new is 1. Thecombination in an airplane, of means operable with the propellin meansof 12 the airplane, other means operab e proportional to the relativespeed of the air and airplane, and a differential indicator controlledby the first named and last named means to indicate propellerefliciency.

2. The combination in an airplane, of means operable in proportion tothe speed means, other means constructed and arranged to be operated bythe relative motion and speed of the 130 7 electrical generator operablepelling means of the air lane,a second free propelling means,

air and airplane, and means controlled by 'the first named and lastnamed means for indicating differences in operation thereof and fordetermining the efiiciency of said propelling means.

3. The combination in an airplane, of an electrical generator operatedby the airplane a second electrical 'generator havmg means to beoperated by the relative motion and speed of the air and airplane, andmeans energized by said generators for indicating the difference incurrent generated and for determining the efiiciency of said propellingmeans;

4. The combination in an airplane, o fan with the progenerator havingpropel ing meansvto operate'same proportional to the relative speedbetween the air and airplane, and a differential galvanometerelectrically connected to said generators and having means forindicating the efliciency of said propelling means.

5. The combination in an airplane, of an electrical generator connectedto the propelling means of the airplane, a second free generator havinga, propeller to operate same according to the relative motion and speedof the an and airplane, and a differential alvanometer having balancedarmature C0118 connected in circuit with the generators, and having anindex and scale of graduations cooperable with the index and graduatedto indicate the efficiency of said propelling means,

THEODORE PtI-IORNE.

